Various high purity systems, such as systems for manufacturing pharmaceuticals, semiconductors, and the like, use high purity diaphragm valves, such as valves made from fluoropolymers. Typical high purity valves have a valve body with an inlet and an outlet separated by a valve seat and a diaphragm. The diaphragm typically has a central stem for sealing against the valve seat to open and close the valve, and an outwardly extending web that seals the cavity of the valve. One existing valve for such a system includes a tongue and groove seal that acts against the valve seat. This tongue and groove design can produce too many particles for a dynamic seal, and therefore is best suited for static sealing applications.
For high purity systems, it is important for the valve diaphragm to maintain a proper seal against the valve seat. In addition, through the numerous cycles of operation, valve seat wear can occur, which reduces the efficacy of the seal. The lack of an effective seal can reduce valve performance in conventional configurations.
In addition, in some circumstances it may be desirable to reduce the thickness of the diaphragm web to increase the valve stroke. A thin diaphragm web, however, is likely to balloon when the valve is pressurized. Some conventional valves incorporate a support structure for reinforcing the diaphragm web as it balloons under pressure. The support structure can be contoured to approximately match the contour of the ballooned diaphragm web, and as the diaphragm web balloons under increased pressure, more of the diaphragm can be pressed into contact with the support surface. The point of contact with the support structure can create an undesirable concentration of stress in the web, which among other drawbacks, may adversely affect the cycle life of the valve.